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Today at the North American International Auto Show, GM announced it has taken a non-controlling equity interest in biology-based renewable energy firm Coskata Inc. The greater-Chicago-based company simultaneously announced that it has developed a proprietary process for converting renewable carbon-rich materials ranging from cornstalks and woodchips to old tires and city trash into clean-burning ethanol at a cost of roughly $1/gallon. A pilot operation will be up and running at Coskata’s R&D headquarters in Warrenville, IL by the end of January, 2008, and a 40,000-gallon commercial demonstration facility under construction at an as yet undisclosed location will go online by the end of the year. General Motors will purchase much of the ethanol produced by this plant for use in the test vehicles at its Milford, MI proving ground. And plans are in the works for a 100-million-gallon/year facility to be up and running by 2011.

GM’s interest is primarily in making ethanol more widely available to increase the popularity of the many models it sells with flex-fuel capability (by 2012, half of GM’s North American production will be flex-fuel capable). The company is also investing extensively in university research and in other firms pursuing different methods of cellulosic ethanol production. GM research suggests that by 2030, one-third of transportation fuel needs can be met by biofuels.

How does the Coskata system work? Like most other cellulosic ethanol conversion processes currently under development, it enlists specialist microorganisms to do much of the work, but rather than using them to break down starches and complex carbohydrates into sugars that can be fermented and distilled, these carefully selected and bred anaerobic (hate oxygen) bacteria assemble ethanol molecules when fed a diet of carbon monoxide and hydrogen gas better known as syngas (the stuff that many towns once used to illuminate their gas streetlamps). The syngas is produced by first superheating the carbon-rich waste materials to 1000 degrees C (1832F). This “gasification” process breaks the long carbon chains into tiny bits in a reaction that actually releases energy after an initial input of energy to reach that temperature. The next step is a scrubber that removes detritus (like steel from tire carcasses and the like) and delivers syngas to the bioreactor. After the designer bugs have feasted on this syngas and water buffet, the ethanol they sweat out passes, along with the water, into an ethanol recovery gizmo that consumes 50 percent less energy than a typical distilling process would. The vaporized low-proof ethanol/water gas is passed through tubes made of a special hydrophilic (loves water) coating that separates the steam, leaving a 99.7-percent pure stream of ethanol coming out the other end while the water gets recycled.

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One of the secrets to this system’s success is energy management. The enormous heat that must be extracted coming out of the gasification step can be harnessed to run electric generating turbines or for uses that may suit a co-located facility. Imagine a paper mill in which this waste heat dries the paper slurry and the waste wood materials feed the reactor. The fact that practically any carbon-rich feedstock can be used enables widespread distribution of ethanol production, limiting the transportation of the feedstock and fuel for greater energy conservation. All of these savings should combine to lower the price of E85 (the popular gasoline blend) to a point where it pays owners of flex-fuel vehicles to tank up with E85 (today most customers are paying a premium in dollars/mile driven out of the greenness of their hearts). Could it be that ethanol is about to become a viable alternative fuel?